1. Field of the Invention
This invention relates to an improved surface mounted medical electrode which performs skin preparation prior to recording biopotential events. The electrode, after application to the skin, is employed to penetrate the epidermal layer of the skin for minimizing motion artifacts. The invention is also directed to a system for skin preparation in conjunction with electrode application, the system including a surface mounted medical electrode and a timed applicator for delivery through the mounted electrode of a prescribed amount of skin preparation by the electrode.
2. Prior Art Relating to the Disclosure
Motion artifacts can be defined as motion induced fluctuation of skin potential which manifests itself as electrical interference which is often superimposed on the desired biopotential signal and minimizes its usefulness for diagnostic and clinical purposes. Motion artifacts have long been a problem in measurement of biopotentials, particularly in longterm electrocardiogram (ECG) monitoring of coronary care patients and in exercise (stress) ECG's. They are generally caused by movement of the patient relative to the electrode applied to the patient's skin, thereby disturbing the skin potential and creating extraneous read-outs on the monitor which either mask the desired biopotential signal or cause a shift in the base line.
It is known that light abrasion of the skin reduces the skin potential as well as minimizes the skin impedance and thereby reduces motion artifacts and improves trace quality. Tam, Hak W., et al, "Minimizing Electrode Motion Artifact by Skin Abrasion", IEEE Trans. on Biomed. Engr., BME-24, No. 2, pp. 134-137 (March 1977).
Although there are many disposable surface mounted electrodes described in the literature and commercially available for cardiac monitoring, reliable trace results from these electrodes is highly dependent on adequate skin preparation prior to application of the electrodes. Proper skin preparation is time consuming as a regular stress ECG requires 3 to 12, generally 10 electrodes. Skin preparation is carried out in various ways. The most common method of preparing the skin is to rub the patient's skin in the areas where the electrodes are to be applied with a gritty material contained in a carrier or to rub the patient's skin with a rough surfaced material to which an alcohol or other solvent is applied. After briskly rubbing the skin, the skin is dried and again rubbed with a dry cloth. If, after the electrodes are applied, a proper trace is not obtained from one or more of the electrodes, the malfunctioning electrodes must be identified, removed, the skin again cleaned and the electrodes reapplied to assure an adequate and accurate trace. Different skin preparation techniques are employed by different individuals. The effectiveness of the skin preparation depends on the technique used as well as the level of skill of the person preparing the skin. Predictably, skin preparation in this manner is highly variable.
Applicants are not aware of any surface mounted medical electrodes suitable for recording biopotential measurements in which the electrode is first applied and then the skin prepared. Such an approach markedly reduces the time consumed in the application of electrodes for recording biopotential events. Also, more reliable, accurate and uniform traces are obtained since the amount and type of skin preparation for each electrode is uniform.